Casimir force in liquid crystals close to the nematic–isotropic phase transition

We show that in nematic liquid crystals, the Casimir effect induced by thermal fluctuations of the orientational order is characterized by a short-range force due to fluctuations of the degree of order and biaxial excitations on top of the long-range interaction caused by director modes, the short-range corrections being important in the vicinity of the phase transition. In the isotropic phase the attraction is entirely short-range. In the case of finite surface coupling, both short- and long-range fluctuation-induced forces are weaker than in the strong anchoring limit.